Camera platform apparatus, method for controlling camera platform apparatus, and storage medium

Abstract

To solve the problem that a burden on an operator for calculating a backlash amount is large.SOLUTION: The pan head device includes a driving source that outputs a driving force, a deceleration mechanism that decelerates the driving force of the driving source, an output shaft that is connected to the deceleration mechanism and to which the decelerated driving force is transmitted and that changes a photographing direction of the imaging unit, an output shaft position detection unit that detects an output shaft position which is a position of the output shaft, and a control unit that controls the driving source. The control unit acquires at least one of a control position which is a position of the drive source and an output shaft position based on a predetermined condition, and obtains a backlash amount based on the acquired control position and the output shaft position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pan head device, a control method for a pan head device, and a program. [Background technology]

[0002] A camera platform is known that houses an imaging device used for surveillance or video distribution, and is equipped with a pan drive unit that rotates the device horizontally and a tilt drive unit that rotates the device vertically, allowing control of the imaging range. The positions of the pan drive unit and tilt drive unit are controlled by a control unit or the like.

[0003] In order to obtain the required torque output, the pan drive unit and tilt drive unit of such a camera platform device may be configured to rotate an output shaft from the motor shaft of a motor via a reduction mechanism having multiple gears. The reduction mechanism has a gap, or backlash, between the multiple gears. This backlash becomes the amount of deviation in position control (also called the backlash amount). Therefore, a technology for determining this backlash amount has been disclosed.

[0004] For example, Patent Document 1 discloses a technology in which a position detector is provided in each drive unit of a television camera, and the drive of each drive unit is controlled based on the output of this position detector. In the technology of Patent Document 1, an operator operates a joystick to drive the drive unit to a preset position, and then detects the position by operating an operation button, and calculates the amount of deviation described above. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-247504 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional technique disclosed in the above-mentioned Patent Document 1, the operator needs to operate a joystick or the like, which places a heavy burden on the operator in calculating the amount of backlash.

[0007] Therefore, the present invention provides a technique that can reduce the burden on the operator in calculating the amount of backlash. [Means for solving the problem]

[0008] In order to solve this problem, for example, the camera platform device of the present invention has the following configuration: A camera platform device for changing the photographing direction of an imaging means for photographing a subject, a drive source that outputs a drive force; a speed reduction mechanism that reduces the driving force of the driving source; an output shaft connected to the reduction mechanism to which the reduced driving force is transmitted, the output shaft changing the imaging direction of the imaging means by the reduced driving force; an output shaft position detection means for detecting the position of the output shaft; a control means for controlling the driving source; Equipped with The control means acquires at least one of a control position, which is the position of the drive source, and the output shaft position based on predetermined conditions, and calculates the amount of backlash based on the acquired control position and output shaft position. [Effects of the Invention]

[0009] According to the present invention, the burden on the operator in calculating the amount of backlash can be reduced. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a diagram illustrating the overall configuration of a control system of the camera platform device according to the embodiment. [Figure 2] 1A and 1B are a plan view and a side view of a pan head device according to an embodiment. [Figure 3] FIG. 2 is a diagram illustrating a drive transmission system of a drive unit according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating the relationship between the motor control position and the output shaft position of the drive unit according to the first embodiment. [Figure 5] FIG. 4 is a flowchart showing a backlash calculation process of the camera head device according to the first embodiment. [Figure 6] FIG. 10 is a diagram illustrating the relationship between the motor control position and the output shaft position of the drive unit according to the second embodiment. [Figure 7] FIG. 10 is a flowchart showing a backlash calculation process of the camera platform device according to the second embodiment. [Figure 8] 10A and 10B are diagrams illustrating another relationship between the motor control position and the output shaft position of the drive unit in the second embodiment. [Figure 9] FIG. 10 is a flowchart showing another backlash calculation process of the camera head device according to the second embodiment. [Figure 10] FIG. 2 is a block diagram showing the hardware configuration of a system control unit. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] (First embodiment) 1 is a diagram illustrating the overall configuration of a control system of a camera platform device 1000 according to an embodiment of the present invention. The overall configuration of the camera platform device 1000 will be described with reference to FIG.

[0013] The camera platform device 1000 holds an imaging device 2000 that captures an image of a subject, and changes the imaging direction, including the pan direction and tilt direction, of the imaging device 2000. The camera platform device 1000 is connected to the imaging device 2000 and a client device 3000. The camera platform device 1000 includes a pan driver 1004, a tilt driver 1005, a system controller 1006, and a communication unit 1007.

[0014] The pan driving unit 1004 performs a panning operation of the camera platform device 1000. The panning operation is an operation of rotating the imaging device 2000 in the left-right direction (i.e., the horizontal direction) around a vertical axis. The pan driving unit 1004 is communicably connected to the system control unit 1006 so as to be able to send and receive signals such as rotation instructions. The pan driving unit 1004 realizes panning using a mechanism that performs the panning operation, such as an actuator such as a brushless DC motor, and an encoder that detects the pan position. In this embodiment, the pan driving unit 1004 is built into either a bottom case 1101 or a turntable 1102, which will be described later.

[0015] The tilt driver 1005 performs a tilt operation of the camera platform device 1000. The tilt operation is an operation of rotating the imaging device 2000 up and down (i.e., vertically) around a horizontal axis extending left and right. The tilt driver 1005 is communicatively connected to the system controller 1006 so as to be able to send and receive signals such as rotation instructions. The tilt driver 1005 realizes tilt drive using a mechanism that performs the tilt operation, such as an actuator such as a brushless DC motor, and an encoder that detects the tilt position. In this embodiment, the tilt driver 1005 is built into either a camera head support 1103 or a camera head 1104, which will be described later.

[0016] The system control unit 1006 is responsible for overall control of the camera platform device 1000. The system control unit 1006 includes a processor such as a CPU (Central Processing Unit). The system control unit 1006 is connected to a client device 3000, which is an information processing device (also called a computer), via a communication unit 1007 so as to be able to send and receive signals. The system control unit 1006 controls the camera platform device 1000 by exchanging signals including commands and responses with the client device 3000. That is, the system control unit 1006 receives commands sent from the client device 3000, analyzes the acquired commands, and executes processing according to the commands. The system control unit 1006 then transmits responses to the commands to the client device 3000. For example, the system control unit 1006 controls the imaging device 2000 based on instructions from commands related to camera control. The system control unit 1006 controls the pan driving unit 1004 and the tilt driving unit 1005 based on instructions from commands related to pan and tilt control to rotate the shooting direction of the imaging device 2000 in the pan direction and tilt direction. The system control unit 1006 receives image data, which is data of an image generated by the imaging device 2000 capturing an image of a subject. The system control unit 1006 transmits the received image data to the client device 3000 via the communication unit 1007. The term "image" may include still images, moving images, video, and data thereof. The system control unit 1006 is equipped with a nonvolatile memory, and stores and registers various data such as preset positions, which will be described later.

[0017] The communication unit 1007 is connected to the client device 3000 via a network, serial communication, etc., and transmits and receives signals to and from the client device 3000. The communication unit 1007 receives commands related to pan / tilt control and camera control from the client device 3000. The communication unit 1007 transmits responses from the system control unit 1006 to the client device 3000. The communication unit 1007 transmits image data received from the imaging device 2000 to the client device 3000.

[0018] The imaging device 2000 includes a lens, an imaging element, and a control circuit. The imaging device 2000 receives light from a subject that is imaged by an imaging optical system including a lens, and converts the optical image of the subject into an electrical signal through photoelectric conversion. The imaging device 2000 generates image data by performing image processing such as development, compression, and encoding on the photoelectrically converted electrical signal. The imaging device 2000 includes an optical zoom control mechanism that can change the imaging angle of view. The imaging device 2000 includes a focus control mechanism that can adjust the focus of the captured image. The imaging device 2000 is connected to the camera platform device 1000. Based on instructions from the client device 3000 acquired from the camera platform device 1000, the imaging device 2000 adjusts the imaging angle of view through zoom control and the focus of the captured image through focus. The imaging device 2000 transmits the generated image data to the camera platform device 1000. As a result, the image data is transmitted to the client device 3000 via the camera platform device 1000 .

[0019] 10 is a block diagram showing the hardware configuration of the system control unit 1006. The system control unit 1006 is, for example, a computer. The system control unit 1006 has a processor 1191, a memory 1192, a storage 1193, an input IF 1195, an output IF 1196, and a bus 1197. The processor 1191, the memory 1192, the storage 1193, the input IF 1195, and the output IF 1196 are connected via the bus 1197 so as to be able to send and receive information to and from each other.

[0020] The processor 1191 is an arithmetic processing device, such as a CPU (Central Processing Unit). The system control unit 1006 may include other processors, such as an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), or a QPU (Quantum Processing Unit), instead of or in addition to the CPU. The processor 1191 implements various functions and executes various processes by reading programs stored in the storage 1193 and expanding the programs in the memory 1192. For example, the processor 1191 executes each step of a backlash calculation process, which will be described later, by reading a computer program. Some or all of the steps of the backlash calculation process may be executed by one or more circuits, such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0021] The memory 1192 is a high-speed readable / writable storage device such as a RAM (Random Access Memory). The memory 1192 functions as a work area when the processor 1191 executes a program. The memory 1192 temporarily stores the program and parameters necessary for executing the program. For example, in the backlash calculation process, the memory 1192 stores the detected motor control position, output shaft position, and backlash amount as the processing result.

[0022] The storage 1193 is a non-volatile storage device such as a hard disk drive (HDD) or a solid state drive (SSD), etc. The storage 1193 holds programs, parameters required for executing the programs, and results of executing the programs even when power is not supplied.

[0023] The input IF 1195 is an interface for receiving information input from an input device, such as a mouse, a keyboard, or a touch panel.

[0024] The output IF 1196 is an interface for outputting information such as processing results to a display device such as a display.

[0025] Next, with reference to FIG. 2, the mechanical configuration of the camera platform device 1000 will be described in detail. FIG. 2 is a plan view and a side view of the camera platform device 1000 according to an embodiment. FIG. 2(a) is a plan view of the mechanical mechanism of the camera platform device 1000 viewed from above the vertical axis. FIG. 2(b) is a side view of the camera platform device 1000. As shown in FIG. 2, the camera platform device 1000 has a bottom case 1101, a turntable 1102, a camera head support 1103, and a camera head 1104. In this embodiment, the imaging device 2000 is built into the camera head 1104. In this embodiment, the pan drive unit 1004 is built into either the bottom case 1101 or the turntable 1102, which will be described later.

[0026] The bottom case 1101 functions as a base for the entire camera platform device 1000, including the pan drive unit 1004 and tilt drive unit 1005. The bottom case 1101 is disposed below the turntable 1102.

[0027] The turntable 1102 carries a camera head support 1103 (described later) and rotates about a vertical axis to drive the turntable in the panning direction, i.e., to pan the camera platform device 1000. The turntable 1102 can rotate in the panning direction from -175 degrees to +175 degrees.

[0028] That is, the mechanism, actuator, and encoder that perform the panning operation of the pan driving unit 1004 are built into either the bottom case 1101 or the turntable 1102. This allows the pan driving unit 1004 to rotate the imaging device 2000 in the pan direction from −175 degrees to +175 degrees. In this embodiment, the pan driving unit 1004 is built into either the bottom case 1101 or the turntable 1102, but may have another configuration. For example, the pan driving unit 1004 may not be built into either the bottom case 1101 or the turntable 1102, but may be arranged in another member.

[0029] The camera head support pillar 1103 extends vertically and is a support pillar that supports the camera head 1104, which will be described later. The camera head support pillar 1103 is disposed on the central axis of the turntable 1102. The camera head support pillar 1103 holds the camera head 1104 on the side opposite the turntable 1102 (here, the upper end).

[0030] The camera head 1104 is hollow. The camera head 1104 houses the imaging device 2000. The camera head 1104 is disposed at the upper end of a camera head support 1103. The camera head 1104 is driven in the tilt direction, that is, performs the tilt operation of the camera platform device 1000, around an axis perpendicular to the vertical axis as the central axis. The camera head 1104 can rotate from -45 degrees diagonally downward and forward to +90 degrees upward, with the horizontal direction being 0 degrees.

[0031] That is, the mechanism, actuator, and encoder that perform the tilt operation of tilt drive unit 1005 are built into either camera head support 1103 or camera head 1104. This allows tilt drive unit 1005 to rotate imaging device 2000 from a downward forward angle of −45 degrees to an upward angle of +90 degrees.

[0032] In addition, in this embodiment, tilt driving unit 1005 is built into either camera head support 1103 or camera head 1104, but may have other configurations. For example, tilt driving unit 1005 may not be built into either camera head support 1103 or camera head 1104, but may be disposed in another member.

[0033] In this way, the camera platform device 1000 of this embodiment can change the imaging direction by rotating the camera head 1104 in the pan direction and tilt direction, allowing the imaging device 2000 to capture an image. Note that the driving ranges of the pan direction and tilt direction of this embodiment are merely examples and are not limited to these. For example, the driving ranges of the pan direction and tilt direction may be configured to allow endless rotation.

[0034] 3 is a diagram illustrating the drive transmission system of the pan driver 1004 and the tilt driver 1005. The configuration of the internal drive transmission system of the pan driver 1004 and the tilt driver 1005 will be described with reference to FIG. 3. The pan driver 1004 and the tilt driver 1005 have roughly the same configuration. The pan driver 1004 and the tilt driver 1005 each have a motor 1201, a motor shaft encoder 1202, a reduction mechanism 1203, an output shaft 1204, and an output shaft encoder 1205.

[0035] The motor 1201 outputs a driving force as a rotational driving force and functions as a driving source for the pan driving unit 1004 and the tilt driving unit 1005. The rotation of the motor 1201 rotates an output shaft 1204, which is a rotation shaft for panning or tilting, via a speed reducing mechanism 1203. As a result, the motor 1201 rotates the imaging device 2000 in either the pan direction or the tilt direction. The motor 1201 may be, for example, a brushless DC motor.

[0036] The motor shaft encoder 1202 is provided on the motor shaft. The motor shaft encoder 1202 may be an incremental encoder or the like. The motor shaft encoder 1202 functions as a position detector that detects the position of the motor shaft (also called the motor control position). The motor shaft encoder 1202 outputs information on the detected motor shaft position to the processor 1191 of the system control unit 1006. The motor shaft encoder 1202 is an example of a drive control position detection means.

[0037] The speed reducing mechanism 1203 is made up of multiple stages of gears and belts, etc. The speed reducing mechanism 1203 reduces the rotation speed of the motor 1201, that is, reduces the driving force, and outputs the required torque to the output shaft 1204.

[0038] The output shaft 1204 is connected to the speed reducer 1203. Therefore, the driving force from the motor 1201, which has been reduced in speed via the speed reducer 1203, is transmitted to the output shaft 1204, and the output shaft 1204 outputs the transmitted rotational drive. As a result, the output shaft 1204 rotates the camera head 1104 in the pan direction or tilt direction, thereby changing the shooting direction of the imaging device 2000.

[0039] The output shaft encoder 1205 is provided on the output shaft 1204. The output shaft encoder 1205 may be an absolute value encoder or the like. The output shaft encoder 1205 functions as a position detector that detects the positions of the output shafts (also referred to as output shaft positions) of the pan driver 1004 and the tilt driver 1005. The output shaft encoder 1205 outputs information on the detected output shaft position to the processor 1191 of the system control unit 1006. The output shaft encoder 1205 is an example of an output shaft position detection means.

[0040] Here, a brushless DC motor has been described as an example of the motor 1201 serving as the drive source, but the motor 1201 is not limited to this and other types of actuators may be used. Also, while the configuration has been shown in which an incremental encoder is used as the motor shaft position detector and an absolute encoder is used as the output shaft position detector, this is not limiting and other types of position detectors may be used. Also, while the configuration has been shown in which the position of the output shaft 1204 is directly detected using the output shaft encoder 1205 provided on the output shaft 1204, this is not limiting. Alternatively, an encoder may be provided on a rotating shaft that rotates from the output shaft 1204 via a reduction mechanism (not shown), and the encoder may be used to indirectly detect the position on the output shaft 1204.

[0041] The processor 1191 of the system control unit 1006 of the camera platform device 1000 of this embodiment registers, in the storage 1193, preset information that associates the position of the pan driver 1004, the position of the tilt driver 1005, the zoom control position of the imaging device 2000, and a preset number. Alternatively, the processor 1191 may register preset information that associates at least one of the position of the pan driver 1004, the position of the tilt driver 1005, and the zoom control position with a preset number. Furthermore, the processor 1191 may register preset information that includes image quality settings and the like in addition to the position of the pan driver 1004, the position of the tilt driver 1005, and the zoom control position.

[0042] Here, the camera platform device 1000 is configured so that the pan driver 1004 and tilt driver 1005 can be remotely controlled via a network and a dedicated line. Therefore, for example, when the processor 1191 receives a predetermined command and a registered preset number from a remote operator, it calls up preset information associated with the preset number. Based on the preset information, the processor 1191 controls the pan driver 1004, tilt driver 1005, and other components to execute a preset function that moves them to a preset position. Furthermore, the system control unit 1006 instructs the pan driver 1004 and tilt driver 1005 to move to the preset position within a predetermined time, thereby realizing a function called "shot" that coordinates and controls the pan and tilt movement times.

[0043] Figure 4 is a diagram illustrating the relationship between the motor control position and output shaft position of the drive unit in the first embodiment. In Figure 4, the horizontal axis represents time, and the vertical axis represents the motor control position and output shaft position. The motor control position represents the position detected by the motor shaft encoder 1202. The output shaft position represents the position detected by the output shaft encoder 1205. The solid line represents the movement trajectory LA of the motor control position detected by the motor shaft encoder 1202. The dotted line represents the movement trajectory LB of the output shaft position detected by the output shaft encoder 1205.

[0044] Assume that at time t0, the motor 1201 is at position me1 in the positive direction. The system control unit 1006 drives the motor 1201 from position me1 in the negative direction to position me0, which is 0 degrees. At this time, the system control unit 1006 controls the motor 1201 based on the motor control position detected by the motor shaft encoder 1202. At this time, the motor control position changes linearly as shown by the movement trajectory LA. However, even if the motor 1201 rotates, there is a section from the start of drive where the output shaft 1204 does not rotate due to backlash in the reduction mechanism 1203. Therefore, the output shaft position, which is the value of the output shaft encoder 1205, does not change from time t0 to time t1.

[0045] Thereafter, the output shaft position detected by the output shaft encoder 1205 begins to change after time t1, and thereafter changes linearly, as shown by the movement locus LB. Then, at time t2, when the motor control position detected by the motor shaft encoder 1202 reaches the 0 degree position, the output shaft position detected by the output shaft encoder 1205 does not become 0 degrees, but takes the value of position oe1.

[0046] Next, the system control unit 1006 drives the motor 1201 from position me0 to position me2 in the negative direction. Assume that at time t3, the motor 1201 is at position me2 in the negative direction. The system control unit 1006 drives the motor 1201 from position me2 in the positive direction to position me0, which is 0 degrees. At this time, the system control unit 1006 controls the motor 1201 based on the motor control position detected by the motor shaft encoder 1202. In this control, the motor control position changes linearly, as shown by movement trajectory LA. Here, there is a certain period from the start of driving, where the output shaft 1204 does not rotate even though the motor rotates, due to backlash in the reduction mechanism 1203. Therefore, the output shaft position detected by the output shaft encoder 1205 does not change from time t3 to time t4, as shown by movement trajectory LB.

[0047] After this, the movement locus LB of the output shaft encoder 1205 begins to change after time t4 and then changes linearly. Here, the time between time t3 and time t4 is approximately the same as the time between time t0 and time t1. Due to the change in the motor control position between time t3 and time t4, the output shaft position approaches the motor control position, and at time t4, the output shaft position and the motor control position become the same position. Then, at time t5, when the motor 1201 reaches the 0-degree position, the output shaft position detected by the output shaft encoder 1205 becomes the position oe2, which is approximately 0 degrees, as shown by the movement locus LB. Here, the difference between the values ​​of positions oe1 and oe2 is the amount of backlash. Therefore, the system control unit 1006 can calculate the amount of backlash without requiring operator operation by calculating the difference in the output shaft position when controlled to the same position (here, the 0-degree position) from both the positive and negative directions. The system control unit 1006 may calculate the amount of backlash by calculating the difference between the motor control position and the output shaft position at time t2. In other words, the system control unit 1006 may calculate the amount of backlash by calculating the difference between the motor control position and the output shaft position at the time when the motor control position becomes 0 degrees. Furthermore, the system control unit 1006 may calculate the amount of backlash by calculating the difference between the movement amount of the motor control position and the movement amount of the output shaft position after time t1 when the output shaft position starts to change.

[0048] Here, the system control unit 1006 calculates the difference between the positions detected by the motor shaft encoder 1202 and the output shaft encoder 1205 when the motor shaft and the output shaft are controlled from the plus and minus directions at the 0 degree position as the amount of backlash, but this is not limited to this. The system control unit 1006 may also calculate the difference between the positions of the motor shaft and the output shaft when the motor shaft and the output shaft are controlled to the same position from the plus and minus directions at another position as the amount of backlash.

[0049] FIG. 5 is a flowchart showing the backlash calculation process of the camera platform device 1000 of the first embodiment. This flowchart is executed by the processor 1191 of the system control unit 1006 reading a computer program from the storage 1193 and loading the program and various data into the memory 1192. The system control unit 1006 executes the flowchart of FIG. 5 upon receiving a command instructing calculation of backlash. In this flowchart, the system control unit 1006 acquires the output shaft position based on predetermined conditions and calculates the amount of backlash based on the output shaft position. For simplicity, the present embodiment will describe the control process in the pan direction, but the control process in the tilt direction also follows a similar flow.

[0050] In step S1001, the system control unit 1006 controls the motor 1201 to drive the pan driving unit 1004 to a position by a predetermined movement amount in the positive direction. The movement amount here is a predetermined movement amount that is sufficient to eliminate backlash, for example, 10 degrees. Note that in the description of this flowchart, the movement amount of the pan driving unit 1004 is, for example, a motor control position detected by the motor shaft encoder 1202 of the motor 1201, and corresponds to the movement trajectory LA.

[0051] In step S1002, the system control unit 1006 controls the motor 1201 to drive the pan driving unit 1004 to the 0 degree position. Since the pan driving unit 1004 was driven from the +10 degree position to 0 degree in step S1001, the system control unit 1006 drives the pan driving unit 1004 10 degrees in the negative direction. Driving to the 0 degree position in step S1002 is an example of a predetermined condition.

[0052] In step S1003, the system control unit 1006 acquires the output axis position as the position of the output axis of the pan driving unit 1004 from the output axis encoder 1205. For example, the system control unit 1006 acquires +0.01 degrees as the output axis position.

[0053] In step S1004, the system control unit 1006 controls the motor 1201 to drive the pan driving unit 1004 in the negative direction to a position by a predetermined movement amount. The movement amount here is set to an amount sufficient to similarly remove backlash, for example, 10 degrees.

[0054] In step S1005, the system control unit 1006 controls the motor 1201 to drive the pan driving unit 1004 to the 0 degree position. In step S1004, the pan driving unit 1004 is driven from the -10 degree position to 0 degree, so the pan driving unit 1004 is driven 10 degrees in the positive direction. Driving to the 0 degree position in step S1005 is an example of a predetermined condition.

[0055] In step S1006, the system control unit 1006 acquires the output shaft position of the pan driving unit 1004 from the output shaft encoder 1205. For example, the system control unit 1006 acquires −0.02 degrees as the output shaft position.

[0056] In step S1007, the system control unit 1006 calculates the amount of backlash from the acquired output shaft position. Specifically, the system control unit 1006 calculates the amount of backlash from the difference between the output shaft position when driven from a position of 10 degrees in the positive direction to a position of 0 degrees and the output shaft position when driven from a position of 10 degrees in the negative direction to a position of 0 degrees. For example, in the case of the above values, the system control unit 1006 calculates the amount of backlash to be 0.03 degrees using the following formula.

[0057] 0.01-(-0.02)=0.03 degrees This causes the system control unit 1006 to end this process.

[0058] The system control unit 1006 also performs the tilt control of the camera platform device 1000 in the same manner as the pan control.

[0059] In this way, the camera platform device 1000 can determine the amount of backlash contained in the pan drive unit 1004 and the tilt drive unit 1005 based on the motor control position and the output shaft position when the pan drive unit 1004 and the tilt drive unit 1005 are controlled to the same position from different directions. This allows the camera platform device 1000 to easily calculate the amount of backlash without requiring any operation by the operator. Furthermore, the camera platform device 1000 can reduce stop position errors due to backlash by using the determined amount of backlash in controlling the pan drive and tilt drive.

[0060] Here, an example has been shown in which pan driving unit 1004 and tilt driving unit 1005 use a brushless DC motor as motor 1201, which is the driving source thereof, and have motor shaft encoder 1202 on the motor shaft that detects the position of the motor, and control motor 1201 using the motor control position by motor shaft encoder 1202 as the control amount for motor 1201, but the present invention is not limited to this. For example, a similar method may be used in a configuration in which a stepping motor is used as motor 1201, which is the driving source, and position control is performed using the number of pulses or steps of the stepping motor as the control amount.

[0061] In the first embodiment described above, the backlash amount is calculated by driving the motor in both the positive and negative directions, but the calculation method is not limited to this. For example, the system control unit 1006 may drive the motor 1201 in one direction and calculate the backlash amount based on the motor control position and output shaft position at the time when the motor control position has been driven to a predetermined position (e.g., the 0-degree position). Specifically, the system control unit 1006 may drive the motor 1201 in one direction and calculate the backlash amount based on the difference between the movement amount of the output shaft position at the time when the motor control position has been driven to a predetermined position (e.g., the 0-degree position) and the movement amount of the motor control position (here, the 0-degree position).

[0062] (Second embodiment) Next, with reference to Figures 6 to 9, a second embodiment will be described, mainly focusing on a method for calculating backlash at the start of drive during reversal operation. The same components as those in the first embodiment will be designated by the same reference numerals, and detailed descriptions thereof will be omitted, with the focus being on differences from the first embodiment. This method of omitting descriptions will also be used in the other embodiments described below.

[0063] Figure 6 is a diagram illustrating the relationship between the motor control position and output shaft position of the drive unit in the second embodiment. In Figure 6, the horizontal axis is the time axis, and the vertical axis represents the motor control position, i.e., the value of the motor shaft encoder 1202, and the output shaft position, i.e., the value of the output shaft encoder 1205. The solid line represents the movement locus LA of the motor shaft encoder 1202. The dotted line represents the movement locus LB of the output shaft encoder 1205.

[0064] FIG. 6 shows the behavior during a reverse operation, that is, when the motor starts moving in the positive direction after being driven in the negative direction. At time t0, the motor 1201 is at position me0, which is 0 degrees. The system control unit 1006 drives the motor 1201 in the positive direction from position me0 to position me2. At this time, the system control unit 1006 controls the motor 1201 based on the motor control position, which is the value of the motor shaft encoder 1202. During this time, the motor shaft encoder 1202 changes linearly, as shown by the movement trajectory LA. However, there is a certain period from the start of driving where the output shaft 1204 does not rotate even though the motor 1201 rotates due to backlash in the reduction gear mechanism 1203. Therefore, the output shaft position, which is the value of the output shaft encoder 1205, does not change from time t0 to time t1. As shown by the movement locus LB, the output shaft position detected by the output shaft encoder 1205 starts to change after time t1, that is, after the value of the motor shaft encoder 1202 has been driven to position me1, and then changes linearly thereafter. At time t2, when the motor control position detected by the motor shaft encoder 1202 reaches position me2, the output shaft position detected by the output shaft encoder 1205 becomes position oe2, which is slightly short.

[0065] Here, the amount of backlash is the difference between the value of position me0 and the value of position me1 detected by the motor shaft encoder 1202. In this way, the amount of backlash can be calculated from the motor shaft encoder value by observing the change in the output shaft encoder 1205 at the start of driving during reverse operation.

[0066] FIG. 7 is a flowchart showing the backlash calculation process of the camera platform device 1000 of the second embodiment. This flowchart is executed by the processor 1191 of the system control unit 1006 reading a computer program from the storage 1193 and loading various programs and data into the memory 1192. The system control unit 1006 executes the flowchart of FIG. 7 upon receiving a pan drive command. In this flowchart, the system control unit 1006 acquires a motor control position based on predetermined conditions and calculates the amount of backlash based on the motor control position. For simplicity, the control process in the pan direction will be described in this embodiment, but the control process in the tilt direction also follows a similar flow.

[0067] In step S2001, the system control unit 1006 determines whether the new drive direction is different from the previous drive direction. If the system control unit 1006 determines that the drive direction is different, that is, that the drive direction has been reversed, the process proceeds to step S2002. On the other hand, if the system control unit 1006 determines that the drive direction is the same, the process ends.

[0068] In step S2002, the system control unit 1006 acquires the motor control position and output shaft position of the pan drive at the start of drive after reversal from the motor shaft encoder 1202 and the output shaft encoder 1205. Here, the system control unit 1006 acquires, for example, 0.01 degrees for both the motor control position and the output shaft position. The start of drive after reversal is an example of a predetermined condition.

[0069] In step S2003, the system control unit 1006 controls the motor 1201 to start driving the pan driving unit 1004.

[0070] In step S2004, the system control unit 1006 determines whether there has been a change in the output axis position. Specifically, the system control unit 1006 acquires the output axis position of the pan drive unit 1004 from the output axis encoder 1205. The system control unit 1006 compares the newly acquired output axis position with the output axis position at the start of drive to determine whether there has been a change. If the system control unit 1006 determines that the output axis position has changed, it proceeds to S2005. On the other hand, if the system control unit 1006 determines that there has been no change in the output axis position, it returns to the processing of S2004 again and continues the processing until it determines that there has been a change. "There has been a change in the output axis position" is an example of a predetermined condition.

[0071] In step S2005, the system control unit 1006 acquires the motor control position from the motor shaft encoder 1202. Here, for example, 0.03 degrees is acquired as the motor control position.

[0072] In step S2006, the system control unit 1006 calculates the amount of backlash from the difference between the motor control position at the start of driving and the motor control position at the start of the change in the output shaft position detected by the output shaft encoder 1205. For example, in the case of the above values, the system control unit 1006 calculates the amount of backlash to be 0.02 degrees using the following formula.

[0073] 0.03-0.01=0.02 degrees This causes the system control unit 1006 to end this process.

[0074] The system control unit 1006 also performs the tilt control of the camera platform device 1000 in the same manner as the pan control.

[0075] In this way, the camera head device 1000 determines the amount of backlash contained in the drive units using the motor control positions during the reversal operations of the pan drive unit 1004 and the tilt drive unit 1005 and the motor control position at the start of the change in the output shaft position. This allows the camera head device 1000 to calculate the amount of backlash without requiring any operation by the operator. Furthermore, by using the determined amount of backlash for control, the camera head device 1000 can reduce stop position errors caused by backlash.

[0076] Figure 8 is a diagram illustrating another relationship between the motor control position and output shaft position of the drive unit of the second embodiment. In Figure 8, the horizontal axis is the time axis, and the vertical axis represents the motor control position, i.e., the value of the motor shaft encoder 1202, and the output shaft position, i.e., the value of the output shaft encoder 1205. The solid line represents the movement trajectory LA of the motor shaft encoder 1202. The dotted line represents the movement trajectory LB of the output shaft encoder 1205.

[0077] FIG. 8 shows the behavior during a reverse rotation, i.e., when the motor 1201 starts moving in the positive direction after being driven in the negative direction. At time t0, the motor 1201 is at position me0 (0 degrees). The system control unit 1006 drives the motor 1201 in the positive direction from position me0 to position me2. During this time, the system control unit 1006 controls the motor 1201 based on the motor control position, which is the value of the motor shaft encoder 1202. During this time, the movement trajectory LA of the motor shaft encoder 1202 changes linearly. Meanwhile, there is a period in which the output shaft position, which is the value of the output shaft encoder 1205, moves slightly from the start of drive. Specifically, from time t0 to time t1, that is, until the motor control position detected by the motor shaft encoder 1202 reaches position me1, the output shaft position detected by the output shaft encoder 1205 changes to position me1. This change represents a phenomenon observed due to the characteristics of the drive transmission system, particularly the spring component of the drive transmission system. This is because, when the drive in the negative direction is completed before the reverse operation of the motor 1201, the backlash is eliminated and the force of the spring component of the drive transmission system is charged into the drive transmission system.

[0078] Subsequently, as the motor rotates in the opposite direction, the charged force is released, causing the output shaft 1204 to rotate a small amount, as shown from time t0 to time t1. After this small amount of rotation, there is a period of time, as described above, during which the output shaft 1204 does not rotate even though the motor 1201 rotates, due to the backlash of the reduction gear mechanism 1203. Specifically, from time t1 to time t2, the output shaft position detected by the output shaft encoder 1205 does not change. After that, once time t2 is reached, that is, when the motor control position detected by the motor shaft encoder 1202 exceeds position me2, the output shaft position detected by the output shaft encoder 1205 begins to change. From that point on, the output shaft position detected by the output shaft encoder 1205 follows a linearly changing path LB. At time t3, when the motor control position detected by the motor shaft encoder 1202 reaches position me3, the output shaft position detected by the output shaft encoder 1205 takes on a value of oe3, which is a slight deviation from the original position.

[0079] In the case of a drive mechanism with such characteristics, the amount of backlash can be measured not at the start of drive, but from the difference between the value of position me1 and the value of position me2 detected by the motor shaft encoder 1202 from the point at which there is no change after the small change after drive start until the next change.

[0080] 9 is a flowchart showing another backlash calculation process of the camera platform device 1000 of the second embodiment. This flowchart is executed by the processor 1191 of the system control unit 1006 reading a computer program from the storage 1193 and loading the program and various data into the memory 1192. The system control unit 1006 executes the flowchart of FIG. 9 when it receives a pan drive command. For simplicity, the control process in the pan direction will be described in this embodiment, but the control process in the tilt direction also follows a similar flow.

[0081] In step S3001, the system control unit 1006 determines whether the new drive direction is different from the previous drive direction. If the system control unit 1006 determines that the drive direction is different, that is, that the drive direction has been reversed, the process proceeds to step S3002. On the other hand, if the system control unit 1006 determines that the drive direction is the same, the process ends.

[0082] In step S3002, the system control unit 1006 acquires the motor control position and output shaft position of the pan drive unit 1004 at the start of drive after reversal from the motor shaft encoder 1202 and the output shaft encoder 1205.

[0083] In step S3003, the system control unit 1006 controls the motor 1201 to start driving the pan driving unit 1004.

[0084] In step S3004, the system control unit 1006 determines whether there is any change in the output shaft position. Specifically, the system control unit 1006 acquires the output shaft position of the pan drive unit 1004 from the output shaft encoder 1205. The system control unit 1006 compares the newly acquired output shaft position with the previously acquired output shaft position, and determines whether there is no change, that is, whether the change has stopped. If the system control unit 1006 determines that the change has stopped and there is no change, it proceeds to S3005. On the other hand, if the system control unit 1006 determines that there is a change, it repeats step S3004 until it determines that the change has stopped and there is no change. The absence of change in the output shaft position after reversal is an example of a predetermined condition.

[0085] In step S3005, the system control unit 1006 acquires the motor control position and output shaft position of the pan drive unit 1004 from the motor shaft encoder 1202 and the output shaft encoder 1205. Here, the system control unit 1006 acquires, for example, 0.02 degrees as the motor control position.

[0086] In step S3006, the system control unit 1006 determines whether there has been a change in the output axis position while it is stopped. Specifically, the system control unit 1006 acquires the output axis position of the pan drive unit 1004 from the output axis encoder 1205. The system control unit 1006 compares the newly acquired output axis position with the output axis position acquired in step S3005 at the time when the output axis position change ceased, and determines whether the output axis position has changed. If the system control unit 1006 determines that the output axis position has changed, that is, that the output axis position change that had once stopped has resumed, the process proceeds to step S3007. On the other hand, if the system control unit 1006 determines that the output axis position has not changed, the process returns to step S3006 and continues until it determines that there has been a change. The resumption of the output axis position change that had once stopped is an example of a predetermined condition.

[0087] In step S3007, the system control unit 1006 acquires the motor control position from the motor shaft encoder 1202. Here, the system control unit 1006 acquires, for example, 0.03 degrees as the motor control position.

[0088] In step S3008, the system control unit 1006 calculates the amount of backlash from the difference between the motor control position when the output shaft position stops changing and the motor control position when the output shaft position starts changing again. The point when the output shaft position stops changing is time t1 in Figure 8. The point when the output shaft position starts changing again is time t2 in Figure 8. For example, in the case of the above values, the system control unit 1006 calculates the amount of backlash to be 0.01 degrees using the following formula.

[0089] 0.03 - 0.02 = 0.01 degrees This causes the system control unit 1006 to end this process.

[0090] The system control unit 1006 also performs the tilt control of the camera platform device 1000 in the same manner as the pan control.

[0091] In this way, the camera head device 1000 determines the amount of backlash contained in the drive units using the motor control positions when the change in the output shaft position stops and when the change resumes after the drive starts during the reversal operation of the pan drive unit 1004 and the tilt drive unit 1005. This allows the camera head device 1000 to calculate the amount of backlash without requiring any operation by the operator. Furthermore, by using the determined amount of backlash for control, the camera head device 1000 can reduce stop position errors caused by backlash.

[0092] Here, the case where the reversal operation is performed at the 0 degree position is shown, but this is not a limitation and measurements may be made when the reversal operation is performed at a predetermined position other than 0 degrees. Also, here, the case where the reversal operation is performed from the minus direction to the plus direction is shown, but this is a limitation and measurements may be made when the reversal operation is performed from the plus direction to the minus direction.

[0093] The above-described embodiments may be combined. For example, the backlash calculation processes of the respective embodiments may be configured to be executable by a single camera platform device, allowing the operator to select one.

[0094] In the above embodiment, an example has been described in which the imaging device 2000 and the pan head device 1000 are separate entities, but the configuration of the pan head device 1000 is not limited to this. For example, the pan head device may be configured integrally with the imaging device.

[0095] (Other Examples) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0096] The disclosure of this specification includes the following pan head device, pan head device control method, and program. (Item 1) A camera platform device for changing the photographing direction of an imaging means for photographing a subject, a drive source that outputs a drive force; a speed reduction mechanism that reduces the driving force of the driving source; an output shaft connected to the reduction mechanism to which the reduced driving force is transmitted, the output shaft changing the imaging direction of the imaging means by the reduced driving force; an output shaft position detection means for detecting the position of the output shaft; a control means for controlling the driving source; Equipped with The control means acquires at least one of a control position, which is a position of the drive source, and the output shaft position based on a predetermined condition, and calculates a backlash amount based on the acquired control position and output shaft position. A pan head device characterized by: (Item 2) a drive control position detection means for detecting a control position of the drive source; Item 2. The pan head device according to item 1, comprising: (Item 3) the drive source is a stepping motor, The control means uses the number of pulses of the stepping motor as a control position of the drive source. 2. The pan head device according to item 1, (Item 4) The control means The backlash amount is calculated based on a position of a first output shaft at a time when the drive source is driven to a predetermined position in a first direction. 4. The pan head device according to any one of items 1 to 3, characterized in that: (Item 5) The control means The backlash amount is calculated based on a difference between a second output shaft position at a time when the drive source is driven to the predetermined position in a second direction opposite to the first direction and the first output shaft position. 5. The pan head device according to item 4, (Item 6) The control means Before driving the drive source in the first direction, the drive source is driven in a second direction opposite to the first direction by a movement amount that can remove the backlash amount. Item 4. The camera platform device. (Item 7) The control means acquiring a first control position of the drive source at a drive start point when the drive source, which is driving in a first direction, starts to drive in a second direction opposite to the first direction; acquiring a second control position of the drive source at a time point when the output shaft position changes after the drive start time point; The difference between the first control position and the second control position is calculated as the backlash amount. 7. The pan head device according to any one of items 1 to 6, characterized in that: (Item 8) The control means acquiring a first control position of the drive source at a point in time when the output shaft position stops changing after the drive source, which is driving in a first direction, starts driving in a second direction opposite to the first direction; acquiring a second control position of the drive source at a time when the change in the output shaft position resumes; The difference between the first control position and the second control position is calculated as the backlash amount. 8. The pan head device according to any one of items 1 to 7, characterized in that: (Item 9) a drive source that outputs a drive force; a speed reduction mechanism that reduces the driving force of the driving source; an output shaft connected to the reduction mechanism to which the reduced driving force is transmitted, the output shaft changing the imaging direction of the imaging means by the driving force; an output shaft position detection means for detecting the position of the output shaft; a control means for controlling the driving source; A control method for a camera platform device for changing the shooting direction of an imaging means for photographing a subject, comprising: At least one of a control position, which is a position of the driving source, and the output shaft position is acquired based on a predetermined condition, and a backlash amount is calculated based on the acquired control position and output shaft position. A method for controlling a pan head device. (Item 10) A program for causing a computer to function as a control means for the camera platform device according to any one of items 1 to 8.

[0097] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0098] 1000: Pan head device, 2000: Imaging device, 3000: Client device, 1004: Pan drive unit, 1005: Tilt drive unit, 1006: System control unit, 1201: Motor, 1202: Motor shaft encoder, 1203: Reduction mechanism, 1204: Output shaft, 1205: Output shaft encoder.

Claims

1. A camera platform device for changing the shooting direction of an imaging means for photographing a subject, a drive source that outputs a drive force; a speed reduction mechanism that reduces the driving force of the driving source; an output shaft connected to the reduction mechanism to which the reduced driving force is transmitted, the output shaft changing the imaging direction of the imaging means by the reduced driving force; an output shaft position detection means for detecting the position of the output shaft; a control means for controlling the driving source; Equipped with The control means acquires at least one of a control position, which is a position of the drive source, and the output shaft position based on a predetermined condition, and calculates a backlash amount based on the acquired control position and output shaft position. A pan head device characterized by:

2. a drive control position detection means for detecting a control position of the drive source; 2. The pan head device according to claim 1, further comprising:

3. the drive source is a stepping motor, The control means uses the number of pulses of the stepping motor as a control position of the drive source.

2. The camera platform device according to claim 1.

4. The control means The backlash amount is calculated based on a position of a first output shaft at a time when the drive source is driven to a predetermined position in a first direction.

2. The camera platform device according to claim 1.

5. The control means The backlash amount is calculated based on a difference between a second output shaft position at a time when the drive source is driven to the predetermined position in a second direction opposite to the first direction and the first output shaft position.

5. The camera platform device according to claim 4.

6. The control means Before driving the drive source in the first direction, the drive source is driven in a second direction opposite to the first direction by a movement amount that can remove the backlash amount. The camera platform device according to claim 4.

7. The control means acquiring a first control position of the drive source at a drive start point when the drive source, which is driving in a first direction, starts to drive in a second direction opposite to the first direction; acquiring a second control position of the drive source at a time point when the position of the output shaft changes after the drive start time point; A difference between the first control position and the second control position is calculated as the backlash amount.

2. The camera platform device according to claim 1.

8. The control means acquiring a first control position of the drive source at a point in time when the output shaft position stops changing after the drive source, which is driving in a first direction, starts driving in a second direction opposite to the first direction; acquiring a second control position of the drive source at a time when the change in the output shaft position resumes; A difference between the first control position and the second control position is calculated as the backlash amount.

2. The camera platform device according to claim 1.

9. a drive source that outputs a drive force; a speed reduction mechanism that reduces the driving force of the driving source; an output shaft connected to the reduction mechanism to which the reduced driving force is transmitted, the output shaft changing the imaging direction of the imaging means by the driving force; an output shaft position detection means for detecting the position of the output shaft; a control means for controlling the driving source; A control method for a camera platform device for changing the shooting direction of an imaging means for photographing a subject, comprising: At least one of a control position, which is a position of the driving source, and the output shaft position is acquired based on a predetermined condition, and a backlash amount is calculated based on the acquired control position and output shaft position. A method for controlling a pan head device.

10. A program for causing a computer to function as the control means for the camera platform device according to any one of claims 1 to 8.

Images